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Date: Thu, 19 Oct 2017 10:18:01 -0700
From: Kees Cook <keescook@...omium.org>
To: "Jason A. Donenfeld" <Jason@...c4.com>
Cc: "Tobin C. Harding" <me@...in.cc>, Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>, 
	"kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>, "Theodore Ts'o" <tytso@....edu>, 
	Linus Torvalds <torvalds@...ux-foundation.org>, Paolo Bonzini <pbonzini@...hat.com>, 
	Tycho Andersen <tycho@...ker.com>, "Roberts, William C" <william.c.roberts@...el.com>, 
	Tejun Heo <tj@...nel.org>, Jordan Glover <Golden_Miller83@...tonmail.ch>, 
	Greg KH <gregkh@...uxfoundation.org>, Petr Mladek <pmladek@...e.com>, 
	Joe Perches <joe@...ches.com>, Ian Campbell <ijc@...lion.org.uk>, 
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <wilal.deacon@....com>, Steven Rostedt <rostedt@...dmis.org>, 
	Chris Fries <cfries@...gle.com>, Dave Weinstein <olorin@...gle.com>, 
	Daniel Micay <danielmicay@...il.com>, Djalal Harouni <tixxdz@...il.com>, 
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5] printk: hash addresses printed with %p

On Wed, Oct 18, 2017 at 10:49 PM, Jason A. Donenfeld <Jason@...c4.com> wrote:
> static void fill_random_ptr_key(struct random_ready_callback *rdy)
> {
>     get_random_bytes(&ptr_secret, sizeof(ptr_secret));
>     static_branch_disable(&no_ptr_secret);
> }
>
> static struct random_ready_callback random_ready = {
>     .func = fill_random_ptr_key
> };
>
> static int __init initialize_ptr_random(void)
> {
>     int ret = add_random_ready_callback(&random_ready);
>
>     if (!ret)
>         return 0;
>     else if (ret == -EALREADY) {
>         fill_random_ptr_key(&random_ready);
>         return 0;
>     }
>
>     return ret;
> }
> early_initcall(initialize_ptr_random);

Tangent: why is the random_ready API designed with -EALREADY? Couldn't
add_random_ready_callback() just perform the call itself and avoid
needing all the callers to check for -EALREADY?

-Kees

-- 
Kees Cook
Pixel Security

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